The present invention relates to heat exchangers that are generally configured comprising a number of internal fluid or gas passages disposed within a surrounding body. In an example embodiment, the internal passages are designed to accommodate passage of a particular fluid or gas in need of cooling, and the body is configured to accommodate passage of a particular cooling fluid or gas used to reduce the temperature of the fluid or gas in the internal passage by heat transfer through the structure of the internal passages. A specific example of such a heat exchanger is one referred to as a shell and tube exchanger, which can be used in such applications as exhaust gas cooling.
Referring to FIG. 1, a shell and tube heat exchanger 10 includes a tube bundle 12 formed from a plurality of individual tubes 14, i.e., internal passages, that are aligned together, positioned next to one another, and that have one or both openings at the tube ends 16 positioned adjacent one another. The tube bundle 12 is disposed within a surrounding shell 18.
The shell is configured having a inlet 20 and outlet 22 to facilitate the passage of a fluid or gas into and out of the shell. Referring now to FIG. 2, in a single-pass shell and tube heat exchanger, the tube bundle 12 is configured so that the tube ends 16 pass through respective ends 24 of the shell. In a dual or multi-pass shell and tube heat exchanger, the tube bundle is configured having one or more 180 degree bends at one of the tube ends to facilitate passage through the shell more than one time.
Referring back to FIG. 1, a tank or manifold 26 is attached to each end of the shell 18 and serves to direct the flow of fluid or gas into and out of the tube bundle. Referring to FIG. 2 again, a header or tube plate 28 is attached to the tube bundle adjacent one or more of the tube bundle ends 16 and forms a connection or attachment point between the tube bundle and a respective end of the shell. As best shown in FIG. 3, the header plate 28 connects the individual tubes 14 in the bundle together, connects the tube bundle to the shell 18, and provides a seal between the shell and the tube bundle so that fluid within the shell does not escape. The tank or manifold is typically attached by weld to the header plate to enable fluid tight transfer of fluid or gas from the tube bundle.
In a shell and tube heat exchanger configured for use in exhaust gas cooling, exhaust gas is passed through the tube bundle for cooling by use of a cooling medium such as water that is passed through the shell. Conventional shell and tube heat exchangers used in such applications are known to be susceptible to leakage due to the nature and geometry of the attachment made between the header plate and the shell. Such leakage is not desired as it can both reduce the operating efficiency of the heat exchanger and ultimately reduce the service life of the heat exchanger.
It is, therefore, desired that a heat exchanger be constructed in a manner that minimizes or eliminates the possibility of unwanted leakage between the tube bundle header plate and the shell. It is desired that such a heat exchanger be constructed in a manner that does not otherwise compromise the operation of the heat exchanger or adversely impact the manner in which the members forming the heat exchanger are attached together. It is desired that such heat exchangers be configured in a manner that does not adversely impact spatial concerns regarding mounting the same for use, thereby permitting easy retrofit use to replace conventional heat exchangers. It is further desired that such heat exchangers be constructed using materials and methods that are readily available to facilitate cost effective manufacturing and assembly of the same.